Hydraulic Crab Steering

[willtech]

Hi guys.
I am currently designing a JCB like steering system for a bespoke vehical. I have two manual hydraulic pumps powering both drive and steering. Here is a breakdown of what each pump does.

Pump one- This pump needs to operate five rotary actuators/motors all in unison. i.e. turn the wheel on the pump one way and they all travel clockwise and anti clockwise turning the wheel the other way.(Figure 1)

Pump Two- This pump needs to operate three of the vetus MTC12510 rams. However, We need some sort of directional Switch/valve as we need to be able to turn all of the wheels together(Figure 2) but also we need to be able to turn the two sets of front wheels
one direction while the back set travel equally in the opposite direction(figure 3) at the change of a lever if possible.

Ihave included a drawing of what I need to do Could any one help with a schematic of some sort.
Thanks, Will

 

[sbozy25]

Why keep it manual?

Why not switch to electronic ECU controlled manifolds? You could then program in the situations you want and run wires to switches in the cab. It would be a much better functioning system that way and the cost would be relatively close in comparison.

I have designed something similar to what you are speaking of. I did as I indicated and used in cab switches to power on solenoids via a program in the ECU. I was then able to open and close valves in the direction and order I wanted based on my program.

Cabbages, knickers, It hasn't got A BEAK!

 

[bradleyelwood]

willtech,

From the looks of the sketch, you have two separate steering requirements, right, one for front axle and one for rear pair, right? I assume that this is a slow speed vehicle, right? The usual arrangement is to steer one end with one hydraulic circuit and the other end with separate circuit. What you have not shown in sketches is the need for simple steering, that is, one end at a time. Both circuits could easily be operated from one pump. Then the operator can steer the front, the rear, or both in combination. If you insist on flipping the steering control from crab to complimentary to simple steering, this can be accomplished with nothing more than swithes, and solonoid valves.

Obviously, my assumptions are that the vehicle is slow speed, such as a boat lift and that you don't need proportional steering, is this right? Another assumption is that you have the ability to connect both rear axles (#2 and #3) with mechanical tie rods so that they share one hydraulic circuit, is this correct? Life gets more complicated if you have to use "follow-up" control such as temposonic cylinders.